GENETIC-VARIATION WITHIN A PARTHENOGENETIC LINEAGE

A clone of the grain aphid Sitobion avenae F, was maintained parthenog enetically over thirty-two generations (n = 344) in a constant environ ment: a new generation being set up by a female selected at random fro m the preceding generation. Genomic DNA from individual aphids was scr eened for genetic stability using RAPD-PCR with a previously tested te n-mer primer. A putative germ-line mutation was noted in generation 14 and somatic mutations were noted in generations 12, 25, 27 and 29. Th ere were no differences in the RAPD-PCR profiles of winged and wingles s morphs and samples tested for symbiotic DNA, No endobiotic fungal or ganism was associated with the clone. Southern blotting and hybridizat ion studies indicated that band additions were of aphid origin. Howeve r, the RAPD-PCR profiles of the germ-line and somatic mutation samples were unique from other aphid clones cultured during the experimental period. This paper documents discernible genetic changes occurring wit hin an animal clonal lineage over time and impacts on the consequences this may have for clonal systems.